Home

Latest Program News

We’ve installed a new time-lapse camera to capture work on the SR 99 Connections Project, which will finish building the ramps and roads that connect SR 99 to the new tunnel.

Seattle Tunnel Partners has completed some of this work, and the remaining work will occur in their existing work zones at the tunnel portals (near the stadiums in the south and near Seattle Center in the north). A new contractor, Scarsella Brothers Inc., will complete this work.

The circled structure above is where southbound traffic will exit the tunnel. The rendering below shows that same tunnel exit in relation to the completed south portal.

SR 99 Connections will start work this month along East Frontage Road South and South Royal Brougham Road, just to the west of Safeco Field. Crews will be installing drainage, illumination and signals, as well as building roadway, curbs and sidewalks. Crews are scheduled to complete this work by the end of May.

The large pit north of Harrison Street that was the tunneling machine Bertha’s finish line has seen a series of dramatic transformations in the past few months. What was once a 90-foot-deep excavation to the west of SR 99/Aurora Avenue North will soon be entirely covered by a concrete lid, capping the future roadways and tunnel maintenance and systems corridors built within.

In early January crews placed 10 girders across the pit. These girders, each 70 feet long and weighing 35 tons, will support the final section of the north portal operations building (the building with the four yellow ventilation stacks) that will be built atop the pit.

This week, crews placed rebar and poured concrete to form a lid across the girders, burying the pit entirely from view.

LEFT: The disassembly pit being built in 2014 (looking north)

RIGHT: The disassembly pit on January 26, 2018 (looking north)

Crews first began excavating the 450-feet-long and 90-feet-deep pit in 2013, in preparation for the completion of tunnel mining. Bertha broke through the pit's southern wall on April 4, 2017. Crews then used that space as the staging area for dismantling the 8,000-ton machine, a tremendous effort which they completed in August.

Once the final piece of the machine was gone, the pit was ready for its second use: becoming part of the tunnel itself. Since August crews have been building walls and decks within the pit that will connect the bored tunnel’s roadways to the short section of cut-and-cover tunnel just to the north. Building these structures has slowly obscured the disassembly pit from view of our construction camera.

View looking north at the pit in July 2014

Pit in 2015, with operations building on its eastern edge well underway

Bertha sits in the pit in early May 2017, between end of tunneling and beginning of disassembly

By November 2017, Bertha is gone and walls and roadway deck are under construction

January 5, 2018: the girders are in place

January 26, 2018: the girders are covered by a concrete pour that caps the pit

This week, Seattle Tunnel Partners shifted gears and moved its road-building operation north for the final 3,000 feet of lower roadway inside the SR 99 tunnel.

Unlike the southbound (upper) roadway, which was built using concrete pours, the northbound (lower) roadway comes together one 22-ton panel at a time. The pre-made panels are trucked into the tunnel, lifted with a specialized crane and joined together to create a functioning highway.

STP installed the first 6,000 feet of lower roadway by hauling the panels from the south portal to a point roughly under Virginia Street and First Avenue. From there, they worked their way south, installing panels as they went. Following the recent completion of the upper roadway at the tunnel’s north end, crews can now deliver panels via the north portal and work south-to-north to finish the final 3,000 feet of lower roadway.

There’s still a lot work ahead before the tunnel is ready for traffic. STP must complete installation and testing of all the operational and safety systems that will make the tunnel function. You can follow the work on our tunnel progress tracker.

There’s a lot to be excited about as the Alaskan Way Viaduct Replacement Program enters 2018. We’re working toward several important construction milestones.

Pushing toward tunnel completion

STP made great progress last year. They finished tunneling, disassembled the tunneling machine and completed the southbound (upper) roadway inside the tunnel. Based on STP’s newest schedule (PDF), the tunnel could open to drivers as soon as this fall. Our goal is to safely open the tunnel to traffic as quickly as possible and begin removing the Alaskan Way Viaduct, but it’s too early to accurately predict a tunnel opening date. Safety and quality remain our top priorities, and will continue to guide all work on the program.

A significant amount of work remains between now and tunnel opening. Crews must complete construction of the roadway within the tunnel, and finish installing many interconnected systems that will be required to operate the tunnel. They also must complete a series of thorough tests and certification by the Seattle Fire Department to ensure the systems are working properly. This includes testing approximately 5,000 individual components and nearly 90 tunnel systems.

The road to tunnel opening

As STP continues their work, construction of final ramp and highway connections to the tunnel is set to begin. The SR 99 Connections Project will build the final connections between the existing highway and the tunnel. Scarsella Bros., Inc. is the contractor for this work, which will be performed under a $22.6 million contract awarded by WSDOT last month.

Scarsella will break ground soon and continue their work throughout this year. When the tunnel is ready to open, SR 99 through downtown Seattle will be closed to traffic for approximately three weeks. Ramps to and from SR 99 will also be affected during this work. The final connections to the tunnel can only be built after the viaduct has been closed because crews must demolish portions of the current roadway to realign SR 99. When these roadway connections are complete, drivers will begin using the new tunnel.

We recognize that this temporary closure of SR 99 will affect the entire region. We’re also aware that the tunnel is one of many projects under construction in downtown Seattle. We will continue to coordinate construction activities with the City of Seattle, Port of Seattle and King County to minimize disruptions to the public. As we always do during major highway closures, we will coordinate with our partner agencies to spread the word, and help keep people and goods moving while crews complete their work.

After the tunnel opens

After the tunnel opens to drivers, we can begin the challenging task of demolishing the Alaskan Way Viaduct. The demolition contractor will also be responsible for decommissioning the Battery Street Tunnel and reconnecting surface streets across Aurora Avenue North. These three projects were combined under a single design-build contract to shave off approximately one year of cumulative construction time.

As we explained this summer, the contractor will determine how the viaduct will be demolished within parameters set in the contract. We plan to select a contractor in late spring, and will share the demolition plan and schedule after the contractor is chosen.

We’re excited about the work that lies ahead in 2018. Stay tuned for new photos, videos and social media updates as we push toward tunnel opening.